Technology

World's oldest wine found at Stone Age sites in Georgia

Scientists say the oldest evidence of winemaking to date has been found at an archeological site in Georgia from the end of the Stone Age.

Residues found in six jars at two ancient village sites dating back to between 5400 to 5000 BC show the chemical signature of wine, reports a team led by researchers at the University of Pennsylvania, the Georgian National Museum, and the University of Toronto.

That makes it 600 to 1,000 years older than evidence of winemaking found in the Zargos Mountains of Iran that had previously been the oldest. (Although evidence of a "grog" made of fermented grapes, hawthorne berries, honey and rice beer has been found in Jiahu, China, from as far back as 7000 BC.)

The new discovery is exciting for a lot of reasons, says Stephen Batiuk, a senior research associate in the Department of Near and Middle Eastern Civilizations and the Archeology Centre at the University of Toronto.

"If you're talking to a wine enthusiast, they love the idea we can push the history of this beverage so far. Us archeologists, we're interested in the human element of it," he told CBC News in an interview.

Batiuk noted that agriculture first started in northern Iraq, northern Syria and southern Turkey, and needed to adapt to different environmental conditions when it spread to places like Georgia, Turkey's northern neighbour.

"To see how we humans adapted and what new products we developed is actually kind of a fun and fascinating thing. And the fact that it was wine and alcohol — I think it says about a lot about human nature."

Ancient villages

Scientists had previously found possible evidence of wine residues at a site called Shulaveris Gora, located about 50 kilometres south of the Georgian capital of Tbilisi.

Batiuk, who had previously studied the spread of wine culture across western Asia and the Middle East, was invited to work with the Georgian National Museum to look for further evidence at both that site and a nearby site called Gadachrili Gora.

During the last part of the Stone Age, known as the Neolithic, those sites were villages of densely packed circular mud-brick homes, each about one to five metres in diameter, interspersed with pits and courtyards. The villages would have been nested in a forested river valley partially surrounded hills and, further away, the snow-capped Caucasus mountains.

Each was spread over an area about the size of an international soccer field and was home to less than 100 people, Batiuk estimates.

They would have grown wheat to make bread. They likely also grew fruit and nut trees. They raised sheep, goats and cattle for meat and milk, and fished in the local stream.

Batiuk and his team hunted for fragments of clay pottery from the bottoms of large storage jars that looked like they might still have some residue stuck to them and sent them to the lab of Patrick McGovern at the University of Pennsylvania for analysis. McGovern used several chemical techniques to look for the fingerprints of the characteristic components of wine — in particular, tartaric acid, which only found in high levels in grapes and not other fruits in the region.

While the technique can't detect whether grape juice was fermented, the researchers noted that it naturally ferments to wine in several days in the temperate climate in that part of Georgia because the yeast that causes fermentation is always found on some grape skins.

In 2015, the first year the Batiuk worked on excavations in the region, none of the samples tested positive for wine.

But in 2016 and 2017, the team worked extra hard to find good samples and they got some good news back.

"I believe I was dancing like a little stick figure under the vines," Batiuk said with a laugh.

The team published their results on Monday in the journal Proceedings of the National Academy of Sciences.

Not a red

The residues were yellowish, Batiuk said, suggesting that the wine was a white and not a red.

He and his colleagues believe it was made from domesticated grapes, but they haven't been able prove that yet because they haven't yet been able to find any preserved grape seeds at the archeological sites.

Domestic grapes produce a lot more fruit than wild grapes because they're hermaphrotidic, with male and female organs on the same flower, so they can self-pollinate. Wild grape flowers are either male or female, so only half the flowers produce fruit, and only if they have been pollinated by insects or wind.

Batiuk says "just from the sheer volume alone" of wine that the neolithic Georgians seemed to be producing, he thinks they would have had to have been growing domesticated grapes. He added that there are 540 different varieties of domestic grapes in that region, suggesting domestication would have to have happened about 8,000 years ago to allow enough time to breed so many kinds.

Besides the U.S., Georgia and Canada, the study also included researchers from France, Italy, Israel and Denmark. It was funded largely by the National Wine Agency of Georgia and the Shota Rustaveli National Science Foundation of Georgia.